Metal monolith for use in a reverse flow reactor

ABSTRACT

High temperature metal monoliths for use in reverse flow reactors and methods of preparing said monoliths are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/507,409, filed on May 17, 2017, the entire contents of which areincorporated herein by reference.

This application also claims the benefit of related U.S. ProvisionalApplication No. 62/507,431, filed on May 17, 2017, the entire contentsof which are incorporated herein by reference.

FIELD

The present application relates to catalytic metal monoliths andprocesses for using same in a reverse flow reactor.

BACKGROUND

Hydrogen production is a valuable process in refining applications.Hydrogen is required for hydroprocessing applications, which generallyrefers to hydrotreating and hydrocracking. Hydrotreating depending onthe type of application, is either to hydrogenate unsaturated bonds,reduce components to remove oxygen, or reduce inorganic components suchas nitrogen or sulfur. This can be done either for reasons of desirablechemistry (e.g., the hydrogenation of benzene to produce cyclohexane forconversion to K-A oil), improving process performance (e.g., selectivedi-olefin hydrogenation forward of a selective butylenes to lightolefins cracking process), or removing unwanted components (e.g.,hydrodesulfurization or hydrodenitrogenation). Hydrocracking refers toan operation that takes a fraction of petroleum called gas oil which isheavy and “cracks” it into smaller molecules that are suitable forincorporation into other petroleum fractions such as gasoline, diesel,and jet fuels. Hydrogen is a key component of all hydroprocessingapplications.

Currently, most hydrogen produced in the United States is made byreforming natural gas via steam reforming. Dry reforming, or acombination of the two known as bi-reforming, can also be used.Steam-methane reforming (SMR) is a process in which high temperaturesteam is used to produce hydrogen from a methane source in the presenceof a catalyst. The reaction is as follows:

CH₄+H₂O→CO+3 H₂

Dry reforming is similar to SMR, but steam is replaced by carbon dioxidein the reforming reaction:

CH₄+CO₂=2H₂+2CO

Steam reforming and dry reforming may also act in concert for a processknown as bi-reforming. As shown hydrogen and carbon monoxide areproduced as a result of these reforming reactions. This mixture can bereferred to as synthesis gas or “syngas.” Syngas generated with a H₂/COmolar ratio between 1 and 10 is useful as a feed for the production ofmethanol, dimethyl ether, lube basestocks, and of course, hydrogen. Thesynthesis gas or “syngas” is a byproduct a variety of refineryprocesses. While most references herein are directed to the methanereforming reaction, it should be appreciated by persons of skill in theart that these reforming processes can apply to heavier petroleumfractions such as ethane, ethanol, propane or even gasoline.

Natural gas reforming methods sometimes utilize a reverse flow reactor(RFR) scheme. In a reverse flow system, flow through a reactor withcatalyst is periodically reversed in order to store heat and/or mass, toregenerate heat/catalysts in situ, or to avoid kinetic limitation of asystem at equilibrium. A basic RFR typically operates as a singlereactor having two zones, a first zone (reaction or combustion zone) anda second zone (recuperator zone). In some descriptions, there is a thirdzone described as a mixer zone which refers to the transition areabetween the reaction zone and the recuperator zone. Both zones willcontain regenerative reactor beds. Regenerative beds, as used herein,are intended to comprise material that are effective in storing andtransferring heat. Regenerative reactor bed(s) means a regenerative bedthat may also be used for carrying out a chemical reaction. Regenerativebeds are generally known in the art and may comprise packing materialsuch as glass or ceramic beads or spheres, metal beads or spheres,ceramic or metal honeycomb materials, ceramic tubes, monoliths, and thelike. In the reaction step of the cycle, the reaction zone is at anelevated temperature and the recuperator zone is at a lower temperature.A reactant feed is introduced to a first end of the reaction zone.

This feed stream picks up heat from the bed and is reacted, usually overcatalyst, to produce the desired reaction. As this step proceeds, atemperature profile is created based on the heat transfer properties ofthe system. When the bed is designed with adequate heat transfercapability, this profile has a relatively sharp temperature gradient,which gradient will move across the reaction zone as the step proceeds.Reaction gas exits the reaction zone at an elevated temperature andpasses through the recuperator zone. The recuperator zone is initiallyat a lower temperature than the reaction zone. As the reaction gaspasses through the recuperator zone, the gas is cooled. As the reactiongas is cooled in the recuperator zone, a temperature gradient is createdin the zone's regenerative bed and moves across the recuperator zoneduring this step. The reaction gas then exits the recuperator zone. Thesecond step of the cycle, referred to as the regeneration step thenbegins.

Regeneration entails transferring heat from the recuperator zone to thereaction zone, to thermally regenerate the reaction beds for thesubsequent reaction cycle. Regeneration gas enters recuperator zone andflows through the recuperator zone and into the reaction zone. In doingso, temperature gradients move across the beds similarly but in oppositedirections to the temperature gradients developed during the reactioncycle. Fuel and oxidant combust at a region proximate to the interfaceof the recuperator zone and the reaction zone. The heat recovered fromthe recuperator zone together with the heat of combustion is transferredto the reaction zone, thermally regenerating the regenerative reactionbeds disposed therein.

U.S. Pat. No. 8,454,911 to Hershkowitz et al. titled “Methane conversionto higher hydrocarbons” (hereinafter “the '911 patent”) describes aprocess converting methane to acetylene using a reverse flow reactorsystem comprising a first and second reactor oriented in a seriesrelationship. In the '911 patent, first and second in-situ combustionreactants are passed independently through a first, quenching reactorbed. Both reactants are heated by the hot quench bed, before they reactwith each other in an exothermic reaction zone (or combustion zone). Toconserve heat, it is preferred that heat from the combustion zoneextends from the first reactor into the second reactor, but is retainedwithin the second reactor so as to conserve energy. After heating thesecond reactor media, in the reverse cycle, methane is flowed throughthe second reactor, from the direction opposite the direction of flowduring the heating step. The methane contacts the hot second reactor totransfer heat to the methane which cracks to acetylene.

U.S. Pat. No. 7,815,873 to Sankaranarayanan et al. titled “Controlledcombustion for regenerative reactors with mixer/flow distributor”(hereinafter “the '873 patent”) describes a process and apparatus forcontrolling the location of the exothermic reaction used forregeneration and fuel/oxidant mixing and flow distribution inreverse-flow, cyclic reaction/regeneration processes. The '873 patentproffers an improved mixing technology to better control thedistribution of heat throughout the RFR.

U.S. Pat. No. 7,217,303 to Hershkowitz et al. titled “Pressure swingreforming for fuel cell systems” (hereinafter “the '303 patent”)described the use of an RFR in a pressure swing process.

Catalysts for natural gas reforming can be structured a number ofdifferent ways including packed beds comprising catalytic beads or morestructured forms including monoliths, metal organic frameworks, hollowfibers, etc. Traditionally monolithic catalyst supports consist of manyparallel channels separated by thin walls that are coated with acatalytic active substance. Current monoliths used in a reverse flowreactor are typically made of a ceramic, such as alumina, and aretherefore catalytically inert. They can also be made of other refractorymaterials due to the ability to withstand high temperature andtemperature cycling. Ceramic monoliths must be washcoated with acatalytic metal in order to perform natural gas reforming or any otherchemistry requiring a catalyst. Additionally, ceramic monoliths have alow volumetric heat capacity and heat conductivity which results ineither increased reactor size, reduced throughput, or both, to processan equal amount of natural gas. Metal monoliths are typically made ofcorrugated foil and rolled, and still require washcoating.

It would be valuable to develop a metal monolithic catalyst support witha higher volumetric heat capacity than achievable with traditionalceramic monoliths. These metal monolith catalyst supports could have ahigher volumetric heat capacity than their ceramic counterparts, whichwould result in reduced reactor size or increased product throughput.Moreover, metal monolith catalyst supports offer greater axial heatconduction versus ceramics and thus can be used to shape the internaltemperature profile of the RFR. Additionally, in certain embodimentsutilizing additive manufacturing techniques, it has been discovered thatotherwise inert metal or metal alloy monoliths can be catalyticallyactivated using an oxido-reductive promotion process. This provides adistinct advantage over the prior art by eliminating the need towashcoat the monolith. Moreover, when additive manufacturing techniquesare utilized, monoliths that do not need to be washcoated open up uniquedesign geometries. Channels through the monolith may be not only round,square, and/or hexagonal, but also in other shapes including but notlimited to quadralobes, trilobes, and/or fractals to maximize surfacearea and volumetric heat capacity. It may also be advantageous for thechannels to have paths other than the straight through the monolith.Circuitous paths and chambers within the 3D printed monolith may alsoenhance the desired characteristics.

SUMMARY

Metal monoliths, methods of preparing said monoliths, and use of saidmonoliths in a reforming reaction are provided herein. In certainaspects, the metal monolith, comprises a monolithic support constructedvia additive manufacturing comprising a metal or metal alloy, whereinthe monolithic support comprises a plurality of cells with channelsextending therefrom; and wherein the monolithic support has a meltingpoint greater than 1200° C. In other aspects, the monolith as avolumetric heat capacity (J/cc/K) greater than 3.5 J/cc/K, e.g. from 3.5to 6 J/cc/K, from 3.5 to 5 J/cc/K. The plurality of cells can formchannels of varying shape, including squares, circles, ovals, hexagons,trilobes, quadrolobes, fractals, or a combination thereof. The channelsthrough the monolith can be linear or non-linear, and can also beinterrupted by void spaces to form chambers within the monolith.

In certain aspects, the metal monolith may further comprise a catalystcoating, such as a zeolite or metal nanoparticles or microparticles. Themonolithic support may include a Group 10 element such as nickel,platinum, and palladium. In certain aspects, the metal alloy is a superalloy, such as Inconel 718. In another aspect, the monolithic supporthas a volumetric heat capacity greater than 3.5 J/cc/K.

Also provided is a method of activating the metal monolith of any of theprevious embodiments comprising, exposing the metal monolith to a cyclicoxidative and reducing environment for a sufficient number of cycles toactivate the metal monolith. In one aspect, the oxidative environmentcomprises at least one of oxygen, carbon dioxide, carbon monoxide,water, combustion byproducts, peroxide, ozone, permanganate, organicacids, halides, or combinations thereof. In another aspect, wherein thereducing environment comprises at least one of methane, ethane, propane,butane, higher C number paraffins, ethylene, propylene, butylene, higherC number olefins, acetylene, methylacetylene-propadiene (MAPD),hydrogen, carbon monoxide, hydrides, hydrogen sulfide, or combinationsthereof. The number is cycles can vary, e.g. from 5-300 cycles or from20-250 cycles. In certain aspects the reducing environment comprisessteam and/or carbon dioxide and hydrocarbons, such as methane, ethane,propane, butane, gasoline, and even whole crude.

Also provided is a method for reforming a feed comprising, providing themetal monolith of any of embodiments described above; activating themetal monolith by either washcoating with a catalyst or exposing themetal monolith to a cyclic oxidative and reducing environment for asufficient number of cycles to activate the metal monolith; introducinga reforming feed to the metal monolith in the presence of heat; whereinthe reforming feed comprises hydrocarbons and steam, carbon dioxide, ora combination thereof; thereby producing CO and H₂; and introducing acombustion feed to the metal monolith comprising O₂ or a combination ofO₂ and N₂. In certain aspects, the reforming feed is methane and greaterthan 70% of the methane is converted to CO and H₂.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a reverse flow reactor.

FIG. 2 is a photograph of two exemplary metal alloy monoliths made viaadditive manufacturing according to the present disclosure.

FIGS. 3A and 3B provide close up images of the metal allow monolithsdepicted in FIG. 2.

FIG. 4 is a cross-sectional view of the axial plane of a metal alloymonolith made via additive manufacturing according to the presentdisclosure.

FIG. 5 is a graphical depiction comparing the catalytic activity betweena 3D printed Inconel 718 metal monolith and an Inconel 718 metal coupon.

DETAILED DESCRIPTION Definitions

In the following detailed description section, specific embodiments ofthe present techniques are described. However, to the extent that thefollowing description is specific to a particular embodiment or aparticular use of the present techniques, this is intended to be forexemplary purposes only and simply provides a description of theexemplary embodiments. Accordingly, the apparatuses and processesencompassed are not limited to the specific embodiments described below,but rather, include all alternatives, modifications, and equivalentsfalling within the true spirit and scope of the appended claims.

Unless otherwise explained, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this disclosure pertains. The singular terms“a,” “an,” and “the” include plural referents unless the context clearlyindicates otherwise. Similarly, the word “or” is intended to include“and” unless the context clearly indicates otherwise. The term“includes” means “comprises.” All patents and publications mentionedherein are incorporated by reference in their entirety, unless otherwiseindicated. In case of conflict as to the meaning of a term or phrase,the present specification, including explanations of terms, control.Directional terms, such as “upper,” “lower,” “top,” “bottom,” “front,”“back,” “vertical,” and “horizontal,” are used herein to express andclarify the relationship between various elements. It should beunderstood that such terms do not denote absolute orientation (e.g., a“vertical” component can become horizontal by rotating the device). Thematerials, methods, and examples recited herein are illustrative onlyand not intended to be limiting

As used herein, the term “activate,” “activates,” “activating,” refersto a transformation from a non-catalytic material to a catalyticmaterial. A catalytic material is one that increases the rate of achemical reaction. Metal catalysts, such as mixed metal oxide orprecious metal oxide catalysts, can be used in a number of differentchemistries. For example, such catalysts can be used in natural gasreforming, water gas shift, oxidative paraffin coupling, paraffindehydrogenation to olefins, methane/ethane dehydrogenation to aromatics,ammonia oxidation to nitrogen oxide, ammonia synthesis, hydrogen cyanideproduction, methanol oxidation to formaldehyde, catalytic combustion,and fuel cells. Activation, as used herein, is evidenced in differentlybased on different chemistries, but in all cases, results in asubstantial increase in reaction products when the reactants are reactedin the presence of an activated material, than when the reactants arereacted in the presence of a non-activated, but similarly structuredmaterial. Specifically, activation may be evidenced by an increase inreaction products of at least 300%, 400%, 500%, 600%, or even 1000% or1500%. In reforming reactions, for example, activation may be indicatedby a step-wise increase in hydrocarbon, such as methane, conversion toCO and H₂—e.g. from 5-15% conversion to 60-90% conversion. A person ofskill in the art should readily be able to discern when a non-catalyticmaterial has become catalytic based on comparative data before and afteractivation as that process is described herein.

As stated above, most hydrogen and/or syngas produced in the UnitedStates is made by reforming natural gas via steam reforming, dryreforming, or a combination of the two known as bi-reforming.Steam-methane reforming (SMR) is a process in which high temperaturesteam is used to produce hydrogen from a methane source in the presenceof a catalyst. The reaction is as follows:

CH₄+H₂O→CO+3 H₂

Dry reforming is similar to SMR, but steam is replaced by carbon dioxidein the reforming reaction:

CH₄+CO₂=2H₂+2CO

Steam reforming and dry reforming may also act in concert for a processknown as bi-reforming. Syngas generated with a H₂/CO molar ratio between1 and 10 is useful as a feed for the production of methanol, dimethylether, lube basestocks, and of course, hydrogen. Hydrogen can then beused in various hydroprocessing applications. While most referencesherein are directed to the methane reforming reaction, it should beappreciated by persons of skill in the art that these reformingprocesses can apply to heavier petroleum fractions such as ethane,ethanol, propane or even gasoline.

Reverse flow reactors (RFRs) are sometimes used to perform natural gasreforming. A generic RFR is depicted in FIG. 1. The RFR operates underforced unsteady-state conditions, created by periodically reversing thefeed flow direction. Therefore, the heat released during the exothermicreaction is trapped inside the reactor bed between two consecutive flowreversals, being used to preheat the cold feed up to the reactiontemperature. As a result, the RFR is an integrated device where bothreaction and heat exchange take place with high thermal efficiency. Withspecific reference to methane reforming, let us assume in FIG. 1 thatthe reactive region is hot and the quench region is cold. As usedherein, “hot” and “cold” are merely terms of relativity and do not referto specific ranges of temperature, but rather to different stages in theRFR reforming cycle.

In the reaction step, a reforming feed is introduced to a first end ofthe reactive region. The reforming feed includes hydrocarbons, such asmethane, and steam, CO₂, or a combination of steam and CO₂. If steam,then the process is referred to as steam reforming. If CO₂, then theprocess is referred to as dry-reforming. If a combination, then theprocess is referred to as bi-reforming. The reforming feed picks up heatfrom the reactive region and is reacted over catalyst, to producehydrogen and carbon monoxide, collectively referred to as syngas, perthe chemical reactions described above. The reforming reaction itself isendothermic and consumes the heat added to the regeneration stepdescribed below. As this step proceeds, a temperature profile is createdbased on the heat transfer properties of the system. When the bed isdesigned with adequate heat transfer capability, such as this case withmetal or metal alloy, this profile has a relatively sharp temperaturegradient, which gradient will move across the reactive region to themixer and quench region. Reaction gas exits the reaction zone at anelevated temperature and passes through the quench region. The quenchregion is initially cold. As the reaction gas passes through the quenchregion, the gas is cooled. As the reaction gas is cooled in the quenchregion, a temperature gradient is created in the quench region's bed andmoves across the quench region. The reaction gas then exits the quenchzone. The second step of the cycle, referred to as the regeneration stepthen begins.

Regeneration entails transferring heat from the quench region to thereactive region, to thermally regenerate the reaction beds for thesubsequent reaction cycle. A regeneration feed or combustion feed,usually O₂, N₂, or a combination thereof for methane reforming, entersquench region and flows through the quench region and into the reactiveregion. In doing so, temperature gradients move across the bedssimilarly but in opposite directions to the temperature gradientsdeveloped during the reaction cycle. Fuel and oxidant combust at aregion proximate to the interface of the quench region and the reactiveregion, i.e. the mixer region. The heat recovered from the quench regiontogether with the heat of combustion is transferred to the reactiveregion, thermally regenerating the monolith supported catalyst in thereactive region. The cycle then repeats.

As mentioned previously, most catalytic monoliths used in reformingcomprise ceramic monolithic substrates washcoated with a catalyticmetal. Metal substrates, typically formed from corrugated, rolled metal,can also be used, but still require washcoating with a catalytic metal.Such materials have comparatively lower volumetric heat capacities thanother materials, such as nickel, iron, or cobalt based metal alloys. Itwould be beneficial to use nickel, iron, or cobalt based metal alloys asmonolithic catalyst supports because of (1) higher volumetric heatcapacities, which could increase product throughput or reduce reactorsize and (2) larger axial heat conduction vs. ceramics that can be usedto “shape” the internal temperature profile of the RFR to maximizeproductivity. Referred to in the industry as “super alloys,” said metalshave excellent mechanical strength, the ability to withstand extremelyhigh temperatures, good surface stability, and resistance to corrosionor oxidation. It is these same qualities that result in difficulties inmachining these metals. See, e.g., Machinability of nickel-base superalloys: a general review, 77 J. OF MAT'L PROCESSING TECH. 278 (May 1,1998). A non-exclusive list of super alloys embodied by the currentdisclosure include: Hastelloy (e.g. C-22, G-30, S, X), Inconel (e.g.587, 597, 600, 601, 617, 625, 706, 718, X750), Waspaloy, Rene alloys,Haynes alloys, Incoloy (e.g. 800, 801, 802, 807, 825, 903, 907, 909),MP98T, TMS alloys, and CMSX single crystal alloys. In terms ofvolumetric heat capacities, Table 1 provides a comparison of typicalceramic materials versus three super alloys. It is clear that the superalloys are superior in this respect.

TABLE 1 Volumetric Heat Capacity (specific heat Material capacity ×density (J/cc/K)) Alumina (ceramic) 3.0 Mullite (ceramic) 2.3 SiC(ceramic) 2.2 Inconel 718 3.6 Hastelloy X 4.0 Nickel 200 4.5

Advances in additive manufacturing have made such materials easier towork with. As used herein, additive manufacturing refers to anytechnology that builds 3D objects by adding layer-upon-layer ofmaterial, whether the material is plastic, metal, ceramic, etc. Additivemanufacturing includes such technologies as 3D printing, direct metallaser sintering (DMLS), selective laser sintering (SLS), etc. As usedherein, the terms 3D printing and additive manufacturing are usedinterchangeably and do not necessarily refer to a specific uniqueprocess unless otherwise stated.

Provided herein is a metal monolith produced by additive manufacturingfor use in an RFR. The metal monolith is composed of a metal, metalalloy, such as a super alloy, and has a melting point above 1200° C.,i.e. above 1250° C., above 1300° C., above 1350° C., or above 1400° C.The monolith described herein can be washcoated with catalyst by anyconventional means. Such washcoating techniques are well described inthe art. See, e.g., Monolithic reactors for environmental applications:A review on preparation technologies, 109 CHEM. ENG'G J. 11 (May 2005).Example catalysts include zeolites and metal nanoparticles ormicroparticles. In addition to increased volumetric heat capacityachievable using these materials, additive manufacturing permits celldensity and open frontal area (OFA) that can be varied from thattypically achievable with ceramic monolith extrusion. OFA's between10-70% are achievable, preferably 25-50% for highly endothermicchemistries, which is beneficial because increased mass results in evenhigher volumetric heat capacity.

In a preferred embodiment, the metal monolith does not requirewashcoating, but rather is catalytically activated through a process ofoxido-reductive promotion. It has been discovered that exposing 3Dprinted metal or metal alloy monoliths to cyclic oxidative and reducingenvironments such as a reforming feed and subsequent combustion feed athigh temperatures can result in activation of an otherwise non-catalyticmonolith. Examples of oxidizing environments include oxygen, carbondioxide, carbon monoxide, water, combustion byproducts, peroxide, ozone,permanganate, organic acids, halides, or combinations thereof. Examplesof reducing environments include methane, ethane, propane, butane,higher C number paraffins, ethylene, propylene, butylene, higher Cnumber olefins, acetylene, methylacetylene-propadiene (MAPD), hydrogen,carbon monoxide, hydrides, hydrogen sulfide, or combinations thereof.The preceding lists are not exhaustive and a person of ordinary skill inthe art would understand that the inert metal alloy starting materialcan be subjected to myriad oxidizing/reducing environment combinations.The crux of the present disclosure is the cyclic nature of the exposureand the oxido-reductive promotion of the inert metal alloy to an activecatalyst as a result. It is believed that any metal alloy with a minimumpercentage of a transition metal, such as nickel, platinum, palladium,rhodium, cobalt, silver, molybdenum, chromium, copper, and/or titaniumcan be transformed into a catalytic metal monolith using the preparationmethods described herein. In certain embodiments, without being bound bytheory, it is believed that nanoparticles or microparticles within themetal alloy are activated and provide the catalytic properties for themetal monoliths described herein. It is important to note that none ofthe metal alloys described in the examples below would be consideredcatalytic to a person of skill in the art before being exposed to themethods of preparation described herein. A minimum percentage of atransition metal means at least 10% by mole, such as 20-80%, such as30-70%, such as 40-60%, such 45-55%.

As used herein, high temperatures include temperatures from 500-1600°C., for example 600-1300° C., for example 700-1200° C. In a preferredembodiment, the cyclic exposure to oxidative and reducing environmentsoccurs between 800-1400° C.

In certain embodiments, a reforming feed and subsequent combustion feedcan provide the cyclic oxidative and reducing environment required toactivate the metal monoliths described herein. The reforming feed caninclude hydrocarbons plus steam, CO₂, or a combination of steam and CO₂.The combustion feed can include fuels plus air or a combination of O₂and N₂. The process of cyclic exposure activates the 3D printed metalstructure for other chemistries requiring a metal catalyst. Withoutbeing bound by theory, the cyclic exposure of the metal alloy may formcatalytic nanoparticles or microparticles that are supported on an oxidelayer on the surface of the metal component. Many combinations of metaloxide layer and catalytic nanoparticles microparticles exist, but oneexample is for IN-718 alloy the nickel nanoparticles or microparticlescan be supported on a primarily chromium oxide layer that also hastitania, molybdenum, alumina, silica, etc.

The process of activating the metal structure can best be described withreference to the examples.

Example 1: Constructing the Metal Monolith

3D printed 1″ long×0.5″ diameter metal monoliths composed of Inconel 718were constructed. Nominally, Inconel 718 alloy comprises nickel(50-55%), chromium (17-21%), tantalum (0.05% max), manganese (0.35%max), carbon (0.08% max), silicon (0.35% max), molybdenum (2.8-3.3%),niobium (4.75-5.5%), titanium (0.65-1.15%), cobalt (1% max), copper(0.3% max), phosphorus (0.015% max), sulfur (0.015% max), boron (0.006%max), and iron (balance). Both 400 cpsi and 800 cpsi (cells per squareinch) were constructed via 3D printing as shown in FIG. 1. The 3Dprinting was completed by DMLS of Inconel 718 powder. FIGS. 2A and 2Bshow that due to the process of metal powder sintering a significantamount of surface area or roughness of the monolith walls is produced.The exterior roughness and increased surface area is likely beneficialto the catalytic activity of the 3D printed monolith as compared to asmoother-channeled monolith. Additionally, as seen particularly in FIG.2B and FIG. 3, each channel is not identical as some variability isobserved in the channel length as well as the sharpness of the cornersfor the square channels. Thus, the monolith does not have to beuniformly 3D printed to ensure that it will be catalytic, but auniformly printed structure could exhibit the same or similarproperties.

Examples 2-17: Laboratory Evaluation of 3D Printed Monoliths

The performance of the 3D printed metal monoliths constructed in Example1 were evaluated for methane reforming (steam, dry, and bi-reforming) ina laboratory scale fixed bed, down-flow reactor. The 1″×0.5″ monolithwas wrapped in a high temperature alumina cloth to prevent bypassing andloaded into a quartz reactor with an inlet diameter of approximately0.6″. A thermocouple was located directly above the top of and directlybelow the bottom of the metal monolith. The methane and carbon dioxideconversion was determined by the disappearance of the reactant. Thesyngas ratio was calculated as the molar ratio of H₂ and CO in theproducts. All conversion for continuous flow experiments are reportedafter 1 hour of lineout. Lineout refers to the time on stream requiredto obtain a constant conversion of reactants to products. In thefollowing experiments, lineout is where constant methane conversion isobserved. All cycling conversions are reported after cycling to lineoutat that temperature except where specifically noted in the table, i.e.Y-5^(th) is after 5 consecutive cycles of oxidation and reforming,Y-250^(th) is after 250 consecutive cycles of oxidation and reforming.The nitrogen included in each run is used as an internal standard forgas chromatograph analysis.

Example 2 shows initial experiments on Monolith A (800 cpsi andsynthesized from Inconel 718 metal powder as described in Example 1).The reforming of methane with water (steam reforming) was performed onthe monolith at a gas hourly space velocity (GHSV) of 10,000 h⁻¹ basedon total monolith volume. The reforming feed had a gas composition of 20vol % CH₄, 70 vol % H₂O, and 10 vol % N₂. At a temperature of 1000° C.,the monolith exhibited minimal catalytic activity converting 15% ofmethane to products with a syngas ratio (H₂/CO) of approximately 3.51.Some initial deactivation of the monolith was observed during the first60 minutes of time on stream, but the conversion was constant at 15% for180 minutes after the initial deactivation.

Examples 3-17 show the experiments on Monolith B (400 cpsi andsynthesized from Inconel 718 metal powder as described in Example 1).Example 3 shows the simultaneous reforming of methane and carbon dioxide(bi-reforming) on Monolith B at a GHSV of 20,000 h ⁻¹ based on totalmonolith volume and a gas composition of 42.9% CH₄, 31.4% H₂O, 15.7%CO₂, and 10% N₂. At a temperature of 800° C. and space velocity of20,000 h-1, the monolith had no appreciable conversion after 60 min ofTOS. While a small amount of hydrogen was observed at the start ofreaction, there was no quantifiable production of CO. Any catalyticsites that were exposed at 800° C. to the bi-reforming feed likely cokedimmediately and became inactive for the methane reforming reaction.

Examples 4-15 show dry reforming (carbon dioxide) of methane with GHSVsof 10,000 h⁻¹ or 20,000 h⁻¹. Example 4 shows an experiment for cyclicaldry reforming of methane with carbon dioxide a GHSV of 20,000 h⁻¹ and agas composition of 43.1% CH₄, 46.9% CO₂, and 10% N₂. The cycling dryreforming experiments included an additional step wherein the reformingfeed is introduced for 1 minute followed by a 7 second nitrogen purgeand then a combustion feed of 5% O₂/N₂ feed is introduced for 1 minutefollowed by a 7 second nitrogen purge. This cycle was repeated for about25 cycles to line out the conversion except when noted in Table 2 below.

Results for cycling dry reforming at 800, 900, and 1000° C. (oven settemperatures) are shown below in Table 1 and the conversion increasesslightly with increasing temperature (Examples 4-6). At 1000° C. theGHSV was halved to 10,000 h⁻¹ and an approximate double in the methaneconversion to 20% was achieved (Example 7). However, after 250 cycles(Example 8) at 1000° C. the methane conversion had increased to 88%.Thus, the catalytic monolith was activated by the cycling procedure toachieve a significantly higher conversion than before the activationprocedure.

A temperature scan from 800 to 1100° C. was then undertaken with amaximum conversion of 94% being achieved at 950° C. (Examples 9-15).After the temperature scan, 1000 cycles of dry reforming were completedat 1000° C. and the methane conversion of 87% was nearly identical tothe conversion after the 250^(th) cycle at 88%. Upon revisiting thebi-reforming non-cycling run condition (Example 16) at 800° C. and aspace velocity of 20,000 the methane conversion is now 78% compared tothe prior methane conversion of 0% before cyclic activation. Whentemperature is increased to 1000° C. (Example 17), the methaneconversion is increased to 98%.

TABLE 2 Reforming GHSV Temper- CH₄ (H₂O + (h⁻¹ × ature Conv. H₂/ Ex.Mon. Cycling CO₂:CH₄) 10⁻³) (° C.) (%) CO 2 A N Steam (3.5:1) 10 1000 153.51 3 B N Bi (1.1:1) 20 800 0 — 4 B Y Dry (1.1:1) 20 800 3 0.3 5 B YDry (1.1:1) 20 900 5 0.4 6 B Y Dry (1.1:1) 20 1000 9 0.5 7 B Y-5^(th)Dry (1.1:1) 10 1000 20 0.5 8 B Y-250^(th) Dry (1.1:1) 10 1000 88 0.9 9 BY Dry (1.1:1) 10 800 77 0.9 10 B Y Dry (1.1:1) 10 850 87 0.9 11 B Y Dry(1.1:1) 10 900 93 0.9 12 B Y Dry (1.1:1) 10 950 94 1.0 13 B Y Dry(1.1:1) 10 1050 68 0.8 14 B Y Dry (1.1:1) 10 1100 55 0.7 15 BY-1000^(th) Dry (1.1:1) 10 1000 87 0.9 16 B Y Bi (1.1:1) 20 800 78 2.117 B Y Bi (1.1:1) 20 1000 98 2.0

Examples 18-27: Laboratory Evaluation of 3D Printed Monoliths withOxidative Treatment

The performance of a separate but equivalent 800 cpsi 3D printed metalmonolith (Monolith C) was evaluated for methane reforming before andafter being exposed to a 5% O₂/N₂ gas composition for 24 hours at 1000°C. The results are shown in Table 3 below. While the monolith had noactivity (Example 18) before being exposed to the oxidative treatment,it did have some activity after the exposure and achieved a 27% methaneconversion (Example 19). Upon cycling with dry reforming, the monolithachieved a 33% methane conversion after 5 cycles (Example 20) comparedto the 20% conversion achieved over Monolith B (Example 7). It isbelieved this activity increase is accelerated by the oxidativetreatment which tends to form a chromium oxide layer on the surface ofthe monolith.

A similar behavior was observed with Monolith C as with Monolith B whilecycling with a conversion efficiency of 85% after 250 cycles (Example21). Additionally, after cyclic activation of the catalyst, thebi-reforming methane conversion of Monolith C was 74% compared to theprior methane conversion of 27% after the oxidative treatment (Example19).

TABLE 3 Reforming GHSV Temper- CH₄ (H₂O + (h⁻¹ × ature Conv. H₂/ Ex.Mon. Cycling CO₂:CH₄) 10⁻³) (° C.) (%) CO 18 C N Bi (1.1:1) 20 800 0 —Exposed to 5% O2/N2 for 24 h at 1000° C. 19 C N Bi (1.1:1) 20 800 27 2.420 C Y-5th Dry (1.1:1) 10 1000 33 0.5 21 C Y-250th Dry (1.1:1) 10 100085 0.9 22 C Y Dry (1.1:1) 10 800 68 0.9 23 C Y Dry (1.1:1) 10 850 82 0.924 C Y Dry (1.1:1) 10 900 90 0.9 25 C Y Dry (1.1:1) 10 950 88 1.0 26 C YDry (1.1:1) 10 1050 77 0.8 27 C Y Dry (1.1:1) 10 1100 68 0.7 28 C N Bi(1.1:1) 20 800 74 2.1

Examples 29-33: Laboratory Evaluation of Monel K 3D Printed Monoliths

3D printed 1″ long×0.5″ diameter metal monoliths composed of Monel Kwere constructed (Monolith D). Nominally, Monel K alloy comprises nickel(63-70%), aluminum (2.3-3.15%), manganese (1.5% max), carbon (0.25%max), titanium (0.35-0.85%), iron (2.0% max), and copper (balance). The3D printing was completed by DMLS of Monel K powder.

Examples 29-33 show bi-reforming and dry reforming of methane with GHSVsof 10,000 h⁻¹ or 20,000 h⁻¹. Example 29 shows an experiment for cyclicalbi-reforming of methane with carbon dioxide a GHSV of 20,000 h⁻¹ and agas composition of 43.1% CH₄, 46.9% CO₂, and 10% N₂. As shown in Table 4below the Monel K monolith exhibited no activity on the first cycle(Example 29). Results for cycling dry reforming at 1000° C. and GHSV of10,000 h⁻¹ shows a substantial increase in activity, from 17% to 82%,between the first cycle (Example 30) and the 100^(th) cycle (Example31). The highest activity observed was 91% (Example 32) at some pointbetween 100 and 1500 cycles. Upon revisiting the bi-reformingnon-cycling run condition (Example 33) at 1000° C. and a space velocityof 20,000 h⁻¹, the methane conversion is now 73% compared to the priormethane conversion of 0% before cyclic activation. The cycling dryreforming experiments included an additional step wherein the reformingfeed is introduced for 1 minute followed by a 7 second nitrogen purgeand then a combustion feed of 5% O₂/N₂ feed is introduced for 1 minutefollowed by a 7 second nitrogen purge. This cycle was repeated for about25 cycles to line out the conversion except when noted in Table 4 below.

TABLE 4 Reforming GHSV Temper- CH₄ (H₂O + (h⁻¹ × ature Conv. H₂/ Ex.Mon. Cycling CO₂:CH₄) 10⁻³) (° C.) (%) CO 29 D N Bi (1.1:1) 20 800 0 —30 D Y Dry (1.1:1) 10 1000 17 31 D Y-5^(th) Dry (1.1:1) 10 1000 82 0.932 D Y-250^(th) Dry (1.1:1) 10 1000 91 0.9 33 D N Bi (1.1:1) 20 1000 732.2

Examples 34-38: Laboratory Evaluation of Hastelloy X 3D PrintedMonoliths

3D printed 1″ long×0.5″ diameter metal monoliths composed of Hastelloy Xwere constructed (Monolith E). Nominally, Hastelloy X alloy comprisesnickel (balance), chromium (20.5-23%), tungsten (0.2-1% max), manganese(1% max), silicon (1% max), molybdenum (8-10%), cobalt (0.5-2.5%), andiron (17-20%). The 3D printing was completed by DMLS of Hastelloy Xpowder.

Examples 34-38 show dry reforming of methane with GHSVs of 10,000 h⁻¹.It must be appreciated at the outset that the beginning cycling data ismissing due to a data recording malfunction. The data below, therefore,indicates activity of the Hastelloy X Monolith E after activation fromcycling has already occurred. In other words, the examples below showthe effect of temperature on conversion efficiency. Table 5 illustratesthat increased temperature will increase activity of 3D printedcomponents. Example 34 shows an experiment for cyclical dry-reforming ofmethane with carbon dioxide, a GHSV of 20,000 h⁻¹, and a gas compositionof 43.1% CH₄, 46.9% CO₂, and 10% N₂. As shown in Table 4 below, MonolithE exhibited 53% conversion during the Example 34 cycle. As temperatureis increased, so is the activity. The highest activity observed was 96%(Example 38). The cycling dry reforming experiments included anadditional step wherein the reforming feed is introduced for 1 minutefollowed by a 7 second nitrogen purge and then a combustion feed of 5%O₂/N₂ feed is introduced for 1 minute followed by a 7 second nitrogenpurge. This cycle was repeated for about 25 cycles to line out theconversion except when noted in Table 5 below.

TABLE 5 Reforming GHSV CH₄ (H₂O + (h⁻¹ × Temp. Conv. H₂/ Ex. Mon.Cycling CO₂:CH₄) 10⁻³) (° C.) (%) CO 34 E Y Dry (1.1:1) 10 800 53 0.7 35E Y Dry (1.1:1) 10 850 64 0.8 36 E Y Dry (1.1:1) 10 900 73 0.9 37 E YDry (1.1:1) 10 950 80 0.9 38 E Y Dry (1.1:1) 10 1000 96 1.0

Examples 39-40: Laboratory Evaluation of Inconel 718 Powder

Inconel 718 powder from the same batch as the monolith constructed asdescribed in Example 1 was set inside a packed bed and subjected tocyclic reducing and oxidative environments. The powder contained anequal amount of Inconel 718 on a per weight basis as the monolithconstructed in FIG. 1. The powder exhibits characteristics that would bethe same or similar as a spherical bead geometry.

Examples 39 and 40 show dry reforming of methane with GHSVs of 10,000h⁻¹ and a gas composition of 43.1% CH₄, 46.9% CO₂, and 10% N₂. As shownin Table 6 below the Inconel 718 powder exhibited very little activity(10% conversion) through five cycles (Example 39). However, after the250th cycle, the methane conversion increased to 84% conversion (Example40). The cycling dry reforming experiments included an additional stepwherein the reforming feed is introduced for 1 minute followed by a 7second nitrogen purge and then a combustion feed of 5% O₂/N₂ feed isintroduced for 1 minute followed by a 7 second nitrogen purge. Thisexamples shows that different geometries of otherwise inert metals canbe activated via oxido-reductive promotion.

TABLE 6 Reforming GHSV CH₄ (H₂O + (h⁻¹ × Temp. Conv. H₂/ Ex. Mon.Cycling CO₂:CH₄) 10⁻³) (° C.) (%) CO 40 Powder Y (5^(th)) Dry (1.1:1) 101000 10 0.8 41 Powder Y (250^(th)) Dry (1.1:1) 10 1000 84 0.9

Example 42: Comparison of Activation of Inconel 718 3D Printed Monolithand Inconel 718 Metal Coupon

An Inconel 718 monolith constructed as described in Example 1 and anInconel 718 metal coupon were both subjected to cyclic reducing andoxidative environments. The monolith and the coupon contained an equalamount of Inconel 718 on a per weight basis. FIG. 5 shows graphicallythe activity increase in dry reforming (carbon dioxide) of methane witha GHSV of 10,000 at 1000° C. and a feed gas composition of gascomposition of 43.1% CH₄, 46.9% CO₂, and 10% N₂.

As shown, the 3D printed monolith is susceptible to activation by themethods described above, while the metal coupon is not.

Additional Embodiments

Embodiment 1. A metal monolith, comprising: a monolithic supportconstructed via additive manufacturing comprising a metal or metalalloy, wherein the monolithic support comprises a plurality of cellswith channels extending therefrom; and wherein the monolithic supporthas a melting point greater than 1200° C.

Embodiment 2. The monolith of embodiment 1, wherein the plurality ofcells with channels form squares, circles, ovals, hexagons, trilobes,quadrolobes, fractals, or a combination thereof.

Embodiment 3. The monolith of any of the previous embodiments, whereinthe plurality of cells with channels comprises channels with non-linearpathways through the monolith.

Embodiment 4. The monolith of any of the previous embodiments, whereinthe monolith further comprises void spaces interrupting the channelsforming chambers within the monolith.

Embodiment 5. The monolith of any of the previous embodiments, furthercomprising a catalyst coating.

Embodiment 6. The monolith of embodiment 5, wherein the catalyst is azeolite.

Embodiment 7. The monolith of embodiment 5, wherein the catalystcomprises metal nanoparticles.

Embodiment 8. The monolith of any of the previous embodiments, whereinthe metal or metal alloy comprises a Group 10 element.

Embodiment 9. The monolith of embodiment 8, wherein the Group 10 elementcomprises one of nickel, platinum, and palladium.

Embodiment 10. The monolith of any of the previous embodiments, whereinthe monolithic support comprises a metal alloy and the metal alloy isone of an Inconel, Hastelloy, and Monel variant.

Embodiment 11. The monolith of any of the previous embodiments, whereinthe monolithic support has a volumetric heat capacity greater than 3.5J/cc/K.

Embodiment 12. A method of activating the metal monolith of any of theprevious embodiments comprising, exposing the metal monolith to a cyclicoxidative and reducing environment for a sufficient number of cycles toactivate the metal monolith.

Embodiment 13. The method of embodiment 12, wherein the oxidativeenvironment comprises at least one of oxygen, carbon dioxide, carbonmonoxide, water, combustion byproducts, peroxide, ozone, permanganate,organic acids, halides, or combinations thereof.

Embodiment 14. The method of embodiments 12 or 13, wherein the reducingenvironment comprises at least one of methane, ethane, propane, butane,higher C number paraffins, ethylene, propylene, butylene, higher Cnumber olefins, acetylene, methylacetylene-propadiene (MAPD), hydrogen,carbon monoxide, hydrides, hydrogen sulfide, or combinations thereof.

Embodiment 15. The method of any of embodiments 12-14, wherein theexposing the metal component to a cyclic oxidative and reducingenvironment includes 5 to 300 cycles.

Embodiment 16. The method of any of embodiments 12-15, wherein theexposing the metal component to a cyclic oxidative and reducingenvironment includes 20 to 250 cycles.

Embodiment 17. The method of any of embodiments 12-16, wherein thereducing environment comprises steam and hydrocarbons.

Embodiment 18. The method of any of embodiments 12-16, wherein thereducing environment comprises CO₂ and hydrocarbons.

Embodiment 19. The method of claim of any of embodiments 12-18, whereinthe oxidative environment comprises O₂.

Embodiment 20. The method of any of embodiments 12-19, wherein theoxidative environment comprises O₂ and N₂.

Embodiment 21. The method of embodiment 17 or 18, wherein thehydrocarbons comprise at least one of methane, ethane, propane, butane,gasoline, and whole crude.

Embodiment 22. A method for reforming a feed comprising, providing themetal monolith of any of embodiments 1-11; activating the metal monolithof any of embodiments 1-11 by either coating with a catalyst or exposingthe metal monolith to a cyclic oxidative and reducing environment for asufficient number of cycles to activate the metal monolith; introducinga reforming feed to the metal monolith in the presence of heat; whereinthe reforming feed comprises hydrocarbons and steam, carbon dioxide, ora combination thereof; thereby producing CO and H₂; and introducing acombustion feed to the metal monolith comprising O₂ or a combination ofO₂ and N₂.

Embodiment 23. The method of embodiment 22, wherein the reforming feedcomprises methane.

Embodiment 24. The method of embodiment 23, wherein greater than 70% ofthe methane is converted to CO and H₂.

1. A metal monolith, comprising: a monolithic support constructed viaadditive manufacturing comprising a metal or metal alloy, wherein themonolithic support comprises a plurality of cells with channelsextending therefrom; and wherein the monolithic support has a meltingpoint greater than 1200° C.
 2. The monolith of claim 1, wherein theplurality of cells with channels form squares, circles, ovals, hexagons,trilobes, quadrolobes, fractals, or a combination thereof
 3. Themonolith of claim 1, wherein the plurality of cells with channelscomprises channels with non-linear pathways through the monolith.
 4. Themonolith of claim 1, wherein the monolith further comprises void spacesinterrupting the channels forming chambers within the monolith.
 5. Themonolith of claim 1, further comprising a catalyst coating.
 6. Themonolith of claim 5, wherein the catalyst is a zeolite.
 7. The monolithof claim 5, wherein the catalyst comprises at least one of metalnanoparticles and microparticles.
 8. The monolith of claim 1, whereinthe metal or metal alloy comprises a Group 10 element.
 9. The monolithof claim 8, wherein the Group 10 element comprises one of nickel,platinum, and palladium.
 10. The monolith of claim 1, wherein themonolithic support comprises a metal alloy and the metal alloy is one ofan Inconel, Hastelloy, and Monel variant.
 11. The monolith of claim 1,wherein the monolithic support has a volumetric heat capacity greaterthan 3.5 J/cc/K.
 12. A method of activating the metal monolith of claim1 comprising, exposing the metal monolith to a cyclic oxidative andreducing environment for a sufficient number of cycles to activate themetal monolith.
 13. The method of claim 12, wherein the oxidativeenvironment comprises at least one of oxygen, carbon dioxide, carbonmonoxide, water, combustion byproducts, peroxide, ozone, permanganate,organic acids, halides, or combinations thereof.
 14. The method of claim12, wherein the reducing environment comprises at least one of methane,ethane, propane, butane, higher C number paraffins, ethylene, propylene,butylene, higher C number olefins, acetylene, methylacetylene-propadiene(MAPD), hydrogen, carbon monoxide, hydrides, hydrogen sulfide, orcombinations thereof.
 15. The method of claim 12, wherein the exposingthe metal component to a cyclic oxidative and reducing environmentincludes 5 to 300 cycles.
 16. The method of claim 15, wherein theexposing the metal component to a cyclic oxidative and reducingenvironment includes 20 to 250 cycles.
 17. The method of claim 12,wherein the reducing environment comprises steam and hydrocarbons. 18.The method of claim 12, wherein the reducing environment comprises CO₂and hydrocarbons.
 19. The method of claim 12, wherein the oxidativeenvironment comprises O₂.
 20. The method of claim 12, wherein theoxidative environment comprises O₂ and N₂.
 21. The method of claim 17,wherein the hydrocarbons comprise at least one of methane, ethane,propane, butane, gasoline, and whole crude.
 22. A method for reforming afeed comprising, providing the metal monolith of claim 1; activating themetal monolith of claim 1 by either coating with a catalyst or exposingthe metal monolith to a cyclic oxidative and reducing environment for asufficient number of cycles to activate the metal monolith; introducinga reforming feed to the metal monolith in the presence of heat; whereinthe reforming feed comprises hydrocarbons and steam, carbon dioxide, ora combination thereof; thereby producing CO and H₂; and introducing acombustion feed to the metal monolith comprising O₂ or a combination ofO₂ and N₂.
 23. The method of claim 22, wherein the reforming feedcomprises methane.
 24. The method of claim 23, wherein greater than 70%of the methane is converted to CO and H₂.